The present invention relates to a terminal block arrangement for a timer device or system in which relatively low values of currents are involved, for the most part, in the timer circuitry which is mounted on a printed circuit (PC) board. The terminal block assembly or arrangement is particularly used in conjunction with electronic timing circuitry to provide the required high current and voltage values involved in switching loads on and off at appropriate times. The on and off switching is carried out by relays judiciously connected to the electronic timing circuitry.
Conventional designs have the characteristic that the components are placed in an area inaccessible to the end user. Typically, a case is provided for the timer device and the front side thereof is provided with a suitable opening for a display and an area for pushbutton controls directed to the selection of the day, hour, or minute, and so forth. At the bottom of the front side of the case, a terminal block is provided for circuitry output, that is, suitable load connections are to be made so as to accomplish the required switching of loads on and off. Such loads can be, for example, lamps, air conditioners, etc.
Depending on the load requirements, conventional design provides connection from the relay which is performing the on and off functions to the terminal area either by the PC board conductors, or by soldering wire from the relay terminals to the board area in which the terminal block is disposed or situated.
Accordingly, it will be apparent to the man skilled in the art that the current design in handling such requirements is deficient because: (1) the PC board conductor is a limiting factor in the current capacity of the timer; in other words, the typical board conductor is very limited in current capacity; (2) using additional wiring simply increases the cost due to the required wire and labor involved in connecting the relay board to the end user terminal board area; additionally, when wiring is used to reach the terminal block, additional soldered or welded contacts have to be made which introduce further contact resistance.
It is therefore a primary object of the present invention to overcome the deficiencies present with conventional design and construction of terminal block arrangements for timer or other electronic devices, which involve components being placed in areas inaccessible to the end user, but in which circuitry output is to be by means of a terminal block to which load connections are to be made. The latter must be accessible but, must importantly, must be capable of carrying the relatively high currents involved, in the order of at least 30 amperes. Furthermore, the heat dissipation must be ample such that UL or other regulatory requirements can be met for the allowable temperature rise.